Gas expansion and absorption process and apparatus therefor



Apr. 17, 1923. 1,452,4M811 J. c. BERTSCH GAS EXPANSION AND ABSORPTIONPROCESS AND APPARATUS THEREFOR Original Filed Oct. 21 1920 a i o E imatted rr. 117, 1923.

NE E S LASZMH ATNT @FHE.

JOHN C. BERTSCH, OF TULSA, OKLAHOMA.

' GAS EXPANSION ABSORPTION PROCESS AND APPARATUS THEREFOR.

Application filed October 21, 1920, Serial No. 418,569. RenewedSeptember 9, 1922. Serial No. 587,231.

To all whom it may concern:

Be it known that I, JoHN C. BERTSCH, a citizen of the United States,residing at Tulsa, in the county of Tulsa and State of Oklahoma, havemade a new and useful Invention in Gas Expansion and Absorption Processand Apparatus Therefor, of which the following is a specification.

This invention relates to improvements in the recovery of vapor from agas by absorption, and forms an extension of the invention covered by myco-pendin application for U. S. Letters Patent, erial No. 415,336.

An object of the invention is the churning of a liquid in the presenceof a gas during the compression of the latter.

Another object of the invention is the alternate mixing and separationof a gas and a liquid in stages for subjecting gas and liquid ofapproximately the same vapor content repeatedly to each other.

Another object of the invention is the circulation of the absorbentliquid during its! distillation and cooling by its own ener y'withoutmechanical aid.

till another object of the invention is the rectification of therecovered fluid and commercial utilization of the resulting by-prodnot.

A further object of the invention is to provide relatively cheap andsemi-portable means for the extraction of vapor'from a gas containingit.

With these and other objects in view, as will more fully appearhereinafter, the invention consists of certain novel features ofprocedure and arrange nents of parts, hereinafter fully described,illustrated in the accompanying drawing and pointed out in the appendedclaims.

In the absorption methods practiced at present. "from 4 to 6 gallons ofabsorbent are circulated per 1000 cubic feet of gas and saturated withthe vapor of the gas to from 3 t0 5 per cent, so that the yield isseldom more than one half of the total vapor content of the gas. Thisinefficiency is caused by the poor mixing and relatively short time ofcontact between gas and liquid, and requires relatively great quantitiesof heat and cooling water for distillation, besides causing a greatwaste of valuable fluid.

Furthermore, an absorption installation of present construction requiresa number of pumps and auxiliary machinery with ex pensive foundationsand buildings, which render impossible the use of units of a relativelysmall capacity and the removal of a plant to other locations in case thegas supply fails. Present day plants require also a relatively largeoperating force, which, together with the unrecoverable loss of unstablefluid produced, results in a relatively high cost of production.

These deects are eliminated by my present invention, in which yields ofup to 95 per cent of the total vapor content of a gas. and a saturationof from 8 to 15 per cent with a circulation of from 10 to 20 gallons ofliquid per 1000 cubic feet of gas are obtained with substantially noloss of gas or liquid, thus reducing the consumption of fuel and coolingwater for distillation greatly.

According to my invention, the only moving part is a gas and liquidhandling rotary pump, which like the expander-absorbers and parts of thedistilling apparatus are selfcontained and require no expensivefoundations and housings, so that'a complete apparatus can be cheaplyconstructed in units of small capacity and semi-portable for a quickremoval and re-installation at other locations.

Owing to the automatic operation of the expander-absorbers and thegravity circulation of liquid and heating agent during distillation, theoperation of an apparatus according to my invention is substantiallyautomatic and requires but little attention, which makes it particularlyadapted for rural districts and isolated places.

Throughout the further description of my invention the terms gas, vaporand liquid are applied in the same sense as in said co-pendingapplication Serial No. 415,336, that is for any gas and liquid ofwhatever composition and from whatever source, respectively, whereas theterm fluid refers only to said liquefied vapor.

In the drawing: a rotary pump 10 receives gas or vapor from a source --Sthrough suction conduit 11 into which a liquid is injected through pipe14, and puts the mix- )ture of gas and liquid under the pressurerequired for doing all the mechanical work during the process. By thisoperation the liquid is heavily agitated at increasing pressure in thepresence of the gas and vapor which are washed and intimately mixed withthe liquid; and owing to the great difl'erence in specific heat,that ofthe liquid being approximately 5 times greater than that of the gas,-andthe greater Weight of the liquid,-which is from 30 to 300 per centgreater than that of the gas,- the compression of the gas occurs in asubstantially isothermal cycle.

The mixture under pressure is discharged through conduit 12 into aseparator 13 in which the bulk of liquid is separated to be used as willbe stated later, the gas andentrained portion of liquid leaving throughpipe 9. If the nature of the gas and the pressure carried requirecooling, or a suitable refrigerant is available for beneficiallyreducing the temperature of the gas before entering theexpander-absorber, the compressed gas may be passed through a cooler G.The liquid under pressure leaves separator 13 through pipe 20 to be fedinto expander C either directly or indirectly by using first itspressure energy in an in ector or pump 21 for feeding with ita quantityof fresh liquid from receiver R- or from cooler L- through pipe 22.

The principles involved in, and work done by the expander-absorbers A---B and C- are fully described in my co-pending ap lication Serial No.415,336, so that it may su cc to describe here only the passage of gasand liquid throu h three of them, while in practice their num er may bemore or less, depending upon the pressure of the gas and effect desired.

The gas passes in succession through ipe 15, expander-A, pipel6,expanderpipe 17, expander C and pipe 18, in the direction indicatedby arrows, and then through a separator 33 for depositing any entrainedliquid, leaving as residue gas through pipe 34 to be suitably disposedof.

The liquid entering through pipe 22 passes in opposite direction to thegas, first through expander C, then through pipe 23, expander B, pipe 25and expander A- during which it is mixed with the gas, elevated andcooledby the expansion of the latter, and separated again from theexpanded gas in each of the expander-absorbers, leaving in a saturatedcondition through pipe 19, the liquid deposited in separator 33gravitating into pipe 22.

For starting the apparatus with gas of normal pressure, the head of theliquid is reduced by withdrawing liquid from either one or all expandersthrough pipes 36 and manifold 37, placing it temporarily into receiver-R-- which is also the storage for fresh liquid, to be graduallyreturned into the expanders through pipe 22 by device 21.

The process so far described answers fully for all cases in which adistillation for the recovery of the absorbent liquid is not desired.Examples of such cases are: the expansion of a gas for the sole purposeof cooling, as in gasoline extraction plants for utilizing high pressuredenuded gas for reducing its pressure; or the expansion of mixtures ofair and gas or vapor for the recovery of the putting it under pressureby the expansion of the gas is also an important feature in all othercases in which distillation is required, because the pressure energyimparted to the liquid is utilized during its further disposition withthe exclusion of mechanical aid, as will more fully appear hereinafter.

\Vhen the gas exists under a suitable pressure, as for example thenatural gas issuing from oil and gas wells; or that available inrefrigerating and gasoline plants operating on the compression system;or that produced in refineries and cracking plants working with pressurestills, pump 10 and separator 13 are dispensed with, and the gas fromsource S- enters expander A directly through pipe 15, being also usedfor operating feeding device 21 by means of pipe 8 shown by dotted line.

In all cases of vapor recovery with the repeated use of the absorbentliquid, distillation is necessary, and the apparatus commonly employedconsists of a heater F-, a still 40, heat exchangers 39 and 41, a liquidcooler L, a vapor condenser V, and a separator 42 with safety valve 43,all suitably interconnected by conduits and provided with valves andregulating devices, not shown on drawing.

As practiced heretofore, the liquid must be pumped from one device tothe other,

, whereas accordin to my invention it passes through the who e apparatusin a continuous cycle, and all the resistances of the system areovercome by the elevation and pressure imparted to the liquid by theexpansion of the gas, thus eliminating all pumps and intermediatereceiving vessels, and.

greatly reducing the operating expenses.

The elevated and saturated liquid leaving expander A under pressurethrough pipe 19 passes in succession through heat ex changer 39, pipe45, coil 46, pipe 47, and atomizer 48, for being pre-heated prior to itsentry into still 40, first by the still vapor in heat exchanger 39, andthen again by the li uid from still 40 in heat exchanger 41. ithin still40, the vapor contained in the preheated liquid is vaporized by means ofa heat carrier circulating in a closed circuit through a heater F, riser54, coils 49 and return pipe 55,.the fuel supply to heater --F- beingindicated by a pipe 56. The

1 heat carrier may be either steam, water or oil, circulating on thegravity system and being maintained at any desired temperature by athermostatically regulated fuel supply to heater --F-. In like manner,the saturated and hot liquid as well as condensate, are circulated bytheir own pressure or heads respectively, which is due to the locationof the different parts with relation to the expander-absorbers and toeach other.

The flow of the saturated liquid to still 40 is caused by the pressureupon it on top of expander --A-, whereas the flow of the hot liquidthrough heat exchangers and cooler, and that of the condensate fromcondenser V is due to gravity. The

pressure upon the saturated liquid in expander A- is just a few poundsless than the initial gas pressure minus the pressure in the still 40,which is but slightly above that in separator 33 for allowing safetyvalve 43 to discharge into pipe 60.

The head required for passing the liquid from still 40 through heatexchanger and cooler into supply pipe 14'and 53, is obtained by placingstill 40 sufficiently high above pump 10, which height is only limitedby the level of the top of expander tube 27. This arrangement eliminatesall pumps as well as constant and close attendance, thus assuring asubstantially automatic operation at a greatly reduced cost ofproduction.

, The vapor generated in still 40- passes through pipe 57, coil 44 andpipe 58 into condenser -V, giving up a part of its heat to the saturatedliquid flowing through heat exchanger 39.

The hot liquid leaves still 40 substantially free of vapor through pipe50 and passes through heat exchanger 41, pipe 51 and cooler L- to becooled therein by the action of cooling water after giving up a part ofits heat to the saturated liquid flowing in coil 46. The so cooledliquid may be further cooled by refrigeration, as will appearhereinafter, or be passed through pipe 52 into pipes 53 and 14 forfeeding expander C and pumplO, respectively, in the manner describedabove.

According to its character, more or less gas is dissolved in the liquidduring the absorption period, producing an unstable fluid and causing aconsiderable loss of gas and vapor by re-evaporation upon exposure tothe atmosphere, which is called weathering.

To overcome this defect, and to produce a stable fluid withoutweathering, and consequently without loss of gas or vapor, and at thesame time utilizing the refrigerating effect of the vaporized portion ofthe condensate for lowering the temperature of the absorbent liquidleaving cooler -L, a rectifier 61 containing a coil 62 and having arelief valve 63 and fluid outlet 64, is connected with conduit 59, theinlet of 0011 62 being in communication with liquid cooler L by pipe 65and its outlet with pipe 52 by a conduit 66.

The fluid enters rectifier 61 through pipe 59 and is sprayed over coil62 by an atomizer 67; the liquid from cooler -L, instead of passingdirectly into pipe 52, is by-passed into coil 62 through pipe 65, andbeing of a relatively higher temperature than the fluid sprayed overcoil 62, causes the evaporation of the lightest and undesirable portion,consisting chiefly of dissolved gas, whereby its temperature is lowered.The so cooled liquid enters pipe 52 through conduit 66, and therectified fluid is withdrawn through pipe 64, whereas the vaporousportion leaves rectifier 61 through relief valve 63 to be disposed ofthrough pipe 68 as a by-product, either as fuel, or as a high tensionfluid by re-compression and liquefaction under a suitable pressure. Thenon-condensable portion of vapor in condenser V- is collected inseparator 42 and escapes through safety valve 43 into pipe 60 throughwhich it passes into separator 33 to be mixed with the residue gas fromexpander C-.

According to the extent of heating desired within rectifier 61, thetemperature of the liquid leaving cooler -L-- may be regulated by theamount of cooling water used; or instead of the liquid from cooler -L,either the gas from separator 13, or the vapor or liquid from heatexchanger 39, or the liquid to or from the heat exchanger 41 may bebypassed through coil 62 in like manner and with a correspondinglygreater or lesser heating effect as that described above.

Having thus fully described my invention, it must be understood that thedrawing is only a diagrammatical view of an apparatus adapted forcarrying out my invention, for which I include as applicable any gas,Vapor or liquid of whatever composition or from whatever source,wherefore it is obvious that on account of the greatly varying characterand composition of the gas vapor and liquid employed in the process, thesame procedure and apparatus cannot be followed in every detail asdescribed and illustrated, so that numerous changes, modifications,additions and omissions may be required for carrying out my invention,without in the least affecting the principles involved.

And because of the intimate nature of process and apparatus, in so faras they are not claimed in my co-pending application for United StatesLetters Patent, Serial No. 415,336, I wish to claim both process andapparatus in the one application, and in the claims I desire to includeany part, not only as named, but as its equivalent.

What I claim as new and desire to secure by Letters Patent is:

1. The absorption process which consists in mixing a gas and a liquidand putting the mixture under pressure; expanding the gas of saidmixture in the act of elevating its liquid and saturating it with thevapor contained in the gas; mechanically separating the expanded gasfrom the saturated liquid and from the latter the vapor by heat;liquefying said vapor and cooling the denuded liquid, and mixing thelatter again with gas.

2. The absorption process which consists in mixing a liquid with a gasunder pressure; expanding the gas of the mixture so formed in the act ofelevating the liquid and saturating it with the vapor of the gas;separating the expanded gas from the saturated liquid and from thelatter the vapor by heat; liquefying said vapor and rectifying theresultant fluid; and cooling the denuded liquid and mixing it again withgas.

3. The absorption process which consists in mixing a gaseous fluid withan absorbent liquid and churning the latter while com-v pressing theformer; expanding the compressed fluid in the act of elevating saidliquid and saturating the latter with the expanding fluid; andseparating the unabsorbed expanded fluid from the saturated liquid.

4. The process of recovering vapor from a gas containing it, whichconsists in mixing said gas with a liquid and churning the latter whileputting the mixture under pressure; alternately separating said mixtureand transferring the resultants to multi stages and mixing them thereinat different pressures; expanding the gas of the mixture in each stagein the act of elevating its liquid and saturating the same with thevapor of the gas; separating and withdrawing the saturated liquid fromthe highest pressure stage and dissociating it by heat; separating andwithdrawing the denuded gas from the lowest pressure stage forcommercial utilization; condensing said dissociated vapor and rectifyingthe resultant fluid; and cooling said dissociated liquid and mixing itwith gas.

5. In a process of absorbing the vapor content of a gas under pressure,the steps of mixing a liquid with said gas and expanding the latter inthe act of elevating said liquid and saturating the same with the vaporof said gas.

6. In a process of absorbing vapor from a gas containing it, the stepsof mixing the gas with a liquid and churning the mixture so formed; thenputting said mixture under pressure and expanding its gas in the act ofelevating its liquid; and saturating said liquid with the vapor of saidgas during said expansion of the latter and separating the expanded gasfrom the saturated liquid.

7. The process of absorbing the vapor content of a gas in multi-stages,which consists in mixing the gas with a liquid and agitat-.

ing the same while putting the mixture under pressure; separating saidmixture and feeding the first or highest pressure stage with thecompressed gas and the last or lowest pressure stagewith liquid by saidliquid under pressure; transferring said gas and liquid under pressurefrom stage to stage in opposite direction to each other while mixing ineach stage the entering gas and liquid; expanding in each stage the gasof the mixture in the act of elevating its liquid and separating thepartially expanded gas from the elevated liquid under pressure;withdrawing from the last stage the denuded gas and from the first stagethe saturated liquid under pressure; dissociating the latter by heat andliquefying the vapor so obtained while cooling the denuded liquid; andcirculating the latter by gravity and said saturated liquid by itspressure energy.

8. In a process of recovering a fluid from a saturated liquid underpressure, the steps of circulating said liquid without mechanical aid byits own pressure energy and dissociating the same by heat; condensingthe dissociated vapor and rectifying the resultant fluid; circulatingthe dissociated liquid by gravity and cooling it; and saturating thecooled liquid while putting it under pressure.

9. An absorption apparatus comprising a plurality of vertical vesselsconnected with each other in series, each being arranged for receivingat the bottom and discharging on top a gas and a liquid and fortransferring the same from vessel to vessel in opposite direction toeach other; a rotary compressor adapted for churning said liquid mixedwith said gas during the compression of the latter and communicatingwith a separator receiving said mixture under pressure, said separatorhaving outlets for gas and liquid communicating with the first and lastof said vessels, respectively; a feeding device in communication withsaid separator a source of said liquid and the last of said vessels;heat exchangers and a still serially connected and communicating withthe liquid discharge of the first of said vessels and receivingsaturated liquid therefrom; a heater communicating with said still inclosed circuit and adapted for gravity circulation of a heat carrierthrough the same; means for condensing the vapor from said still and forrectifying the resultant fluid; and means for cooling and delivering thedenuded liquid from said still to said compressor and feeding device.

10. In an absorption apparatus in combination with vertical absorbersand sources of gas and liquid, a rotary compressor adapted forcompressing a gas mixed with a liquid and churning the latter during thecompression of the former, having its inlet communicating with thesources of gas and liquid and its outlet with a separator into which thechurned mixture under pressure is discharged, said. separator havingoutlets for gas and liquid under pressure; a feeding devicecommunicating with the liquid outlet of said separator the source ofliquid and said absorbers and adapted for feeding the latter with saidliquid; and a conduit making communication between the absorbers and gasoutlet of said separator.

11. In an absorption apparatus in combination with a vapor condenserfluid receiver heat exchangers and liquid coolers, a fluid rectifier incommunication with said condenser and receiver, having means for heatingthe fluid and vaporizing its unstable portion and provided with meansfor separating and discharging the rectified fluid and unstable vapor,said heating means com municating with said heat exchangers and liquidcoolers for utilizing the respective liquids circulating through them asheating agents; and means for converting said unstable vapor intocommercial by-products of the process.

12. An absorption apparatus comprising a rotary compressor adapted formixing a gas with a liquid and churning the latter during thecompression of the gas, having an inlet communicating with sources ofgas and liquid and an outlet with a separator receiving said mixtureunder pressure and having outlets for gas and liquid; a feeding devicecommunicating with the liquid outlet of said separator and source ofliquid; a series of vertical vessels each having bottom inlets and topoutlets for gas and liquid, said gas inlets and outlets and liquidinlets and outlets communicating with each other, respectively, inopposite directions to each other except the gas inlet and liquid outletof the first of said vessels and the liquid inlet and gas outlet of thelast of said vessels; conduits connecting the gas outlet of saidseparator with the gas inlet of the first of said vessels and the liquidinlet of the last of said vessels with said feeding device; heatexchangers and an elevated still serially connected and in communicationwith. the liquid outlet of the first of said vessels and adapted forgravity circulation of the denuded liquid, said still having means forcirculating a heat carrier; a heater communicating with the heatingmeans of said still and arranged for circulating the heat carrier inclosed circuit; a vapor condenser in communication with said still andreceiving vapor therefrom; a fluid rectifier communicating with saidcondenser and a source of heat and arranged for circulating a heatcarrier in closed circuit through the same and for withdrawing therectified fluid and automatically expelling the unstable vapor; meansfor cooling said denuded liquid and supplying it to said compressor andfeeding device, and means for abstracting heat from the contents of saidcondenser and cooling means by a cooling agent.

In testimony whereof, I have hereunto subscribed my name this 18th dayof October, A. D. 1920. JOHN C. BERTSCH.

